Dibromomethane

• Catalog No.: A10456
• CAS Number: 74-95-3
• M. F.: CH2Br2
• M. W.: 173.83458
• Purity: 99%, stab. with 50ppm BHT

SYNONYMS

• Title: 二溴甲烷
• IUPAC name: dibromomethane
• IUPAC Traditional name: dibromomethane
• Synonyms: Methylene bromide

DATABASE IDS

• Beilstein Number: 969143
• MDL Number: MFCD00000168
• CAS Number: 74-95-3
• Merck Index: 146061
• EC Number: 200-824-2

PROPERTIES

• Purity: 99%, stab. with 50ppm BHT
• Boiling Point: 96-98°C
• Density: 2.495
• Melting Point: -53°C
• Refractive Index: 1.5410
• GHS Hazard statements: H332-H412
• European Hazard Symbols: X
• GHS Precautionary statements: P261-P273-P271-P304+P340-P312-P501A
• Risk Statements: 20-52/53
• RTECS: PA7350000
• Safety Statements: 24-61
• TSCA Listed: 是
• Hazard Class: 6.1
• UN Number: UN2664
• Packing Group: III

REFERENCES

• For in situ formation of dibromomethyllithium by reaction with lithiated 2,2,6,6-Tetramethylpiperidine, A18712, and use in a one-pot ester homologation sequence, safer and more convenient than the classical Arndt-Eistert (diazomethane) method, see: Org. Synth. Coll., 9, 426 (1998):
  
• Reaction with NaHMDS generates monobromocarbene, which reacts with alkenes to give bromocyclopropanes: Synthesis, 201 (1972). It can also be generated by reaction with diethylzinc in the presence of O₂: J. Chem. Soc., Chem. Commun., 364 (1975).
• The Simmons-Smith reaction (see Diiodomethane, A15457) may be extended to the use of dibromomethane in the cyclopropanation of simple electron-deficient alkenes, using a reducing agent prepared from NiBr₂, NaI and Zn: Bull. Chem. Soc. Jpn., 56, 1025 (1983); or with CuCl/Zn: J. Org. Chem., 55, 2491 (1990).
• With TiCl₄/Zn, methylenation of ketones occurs, as a useful mild alternative to the Wittig reaction: Tetrahedron Lett., 23, 4293 (1982); Org. Synth. Coll., 8, 386 (1993). For a variant using Zn, CuCl and catalytic TiCl₄, see: J. Org. Chem., 54, 2388 (1989).
• With alcohols, formaldehyde acetals can be formed under phase-transfer conditions: Bull. Chem. Soc. Jpn., 66, 2149 (1993). Diols give methylenedioxy derivatives, which are components of many biologically-important molecules. For use of KF in DMF as base in the methylenation of catechols, see: Tetrahedron Lett., 3361 (1976). KOH in DMSO has been recommended for the methylenation of base-stable carbohydrate diols: Synthesis, 421 (1982). For the methylenation of ribonucleosides under phase-transfer conditions, see: Synthesis, 715 (1981).